Grace Mugabe will avoid prosecution for allegedly whacking 20-year-old Gabriella Engels inside a South African hotel Sunday night for hanging out with the first lady’s two sons.

Even so, border posts are on “red alert” to prevent Mugabe from fleeing the country and police insist she won’t receive any special treatment.

But a senior government source told Reuters there was “no way” the wife of 93-year-old President Robert Mugabe would be charged due to the diplomatic fallout that would ensue.

“There would obviously be implications for our relations with Zimbabwe. Sadly the other countries in the region are watching us and how we are going to act,” the source added. “What is likely to happen is that she will be allowed to go back home, and then we announce that we’ve granted diplomatic immunity and wait for somebody to challenge us.”

Gabriella Engels during a media conference in Pretoria, South AfricaAP

Initially, it was believed that Mugabe wouldn’t qualify for immunity because she was in South Africa for medical treatment — not on official business.

The source told Reuters the government was expecting to be challenged in court over its decision.

Engels said Mugabe flew into a rage at the hotel and accused her of living with her sons, Robert and Chatunga.

“She flipped and just kept beating me with the plug. Over and over,” Engels said. “I had no idea what was going on. I was surprised … I needed to crawl out of the room before I could run away.”

The alleged beatdown left Engels with a nasty gash on her forehead that required 14 stitches.

The pretty model has lawyered up with Gerrie Nel, the prosecutor who secured a murder conviction against double-amputee Olympic track star Oscar Pistorius.

Her mother, Debbie, said it would be “very sad” if Mugabe were allowed to leave the country.

“Gerrie Nel and the team have contingency plans,” Debbie said. “They will run with it.”